Deposition process for solar cell front contact

Abstract

A method includes depositing an acid over a portion of a buffer layer of a solar cell substrate. A front contact material is deposited over the buffer layer, such that the front contact material does not bond to the portion of the buffer layer having the acid on it. Thus, the front contacts of adjacent solar cells of the solar cell substrate are formed with a separation between them.

1 . A method comprising:
 depositing an acid over a portion of a buffer layer of a solar cell substrate; and   depositing a front contact material over the buffer layer, such that the front contact material does not bond to the portion of the buffer layer having the acid thereon, thereby forming front contacts of adjacent solar cells of the solar cell substrate with a separation therebetween.   
     
     
         2 . The method of  claim 1 , wherein the step of depositing the acid includes printing the acid on the buffer layer. 
     
     
         3 . The method of  claim 2 , wherein the printing is performed using a printing head of a scribing tool. 
     
     
         4 . The method of  claim 2 , wherein the printing is performed while a P 2  scribe line is being mechanically scribed in the solar cell substrate, the P 2  scribe line penetrating the buffer layer and an absorber layer of the solar cell substrate. 
     
     
         5 . The method of  claim 1 , wherein the separation is a P 3  line of the solar cell substrate, and the P 3  line is formed without mechanical scribing. 
     
     
         6 . The method of  claim 1 , wherein the acid is deposited using a mask. 
     
     
         7 . The method of  claim 1 , wherein the step of depositing the front contact material comprises chemical vapor deposition. 
     
     
         8 . A method comprising:
 forming a back contact over a solar cell substrate;   forming an absorber over the back contact;   forming a buffer layer over the absorber;   depositing an acid over a portion of the buffer layer; and   depositing a front contact material over the buffer layer, such that the front contact material does not bond to the portion of the buffer layer having the acid thereon, thereby forming front contacts of adjacent solar cells of the solar cell substrate with a separation therebetween.   
     
     
         9 . The method of  claim 8 , wherein the step of depositing the acid includes printing the acid on the buffer layer using a printing head of a scribing tool. 
     
     
         10 . The method of  claim 9 , wherein the printing is performed while a P 2  scribe line is being mechanically scribed in the solar cell substrate, the P 2  scribe line penetrating the buffer layer and absorber layer of the solar cell substrate. 
     
     
         11 . The method of  claim 10 , wherein the separation is a P 3  line of the solar cell substrate, and the P 3  line is formed without mechanical scribing. 
     
     
         12 . The method of  claim 8 , wherein the acid is deposited using a mask. 
     
     
         13 . The method of  claim 8 , wherein the step of depositing the front contact material comprises metal organic chemical vapor deposition. 
     
     
         14 . The method of  claim 8 , wherein the acid comprises HCl or H 2 SO 4 . 
     
     
         15 . The method of  claim 14 , wherein the buffer layer comprises ZnO, and the acid is solution of HCl in water, with a concentration of the HCl in a range from about 0.2 mol to about 1.0 mol. 
     
     
         16 . The method of  claim 14 , wherein the acid further comprises an additive for controlling spreading of the acid. 
     
     
         17 . The method of  claim 16 , wherein the additive comprises silicon oxide particles. 
     
     
         18 - 20 . (canceled) 
     
     
         21 . A method comprising:
 forming a back contact over a solar cell substrate;   forming an absorber over the back contact;   forming a buffer layer over the absorber;   depositing an acid over a portion of the buffer layer; and   depositing a front contact material over the buffer layer, such that the front contact material does not bond to the portion of the buffer layer having the acid thereon, thereby forming a separation opening that extends from a top surface of the front contact material to a top surface of the buffer material.   
     
     
         22 . The method of  claim 21 , wherein the step of depositing the acid includes printing the acid on the buffer layer using a printing head of a scribing tool. 
     
     
         23 . The method of  claim 9 , wherein the printing is performed while a P 2  scribe line is being mechanically scribed in the solar cell substrate, the P 2  scribe line penetrating the buffer layer and absorber layer of the solar cell substrate.